Grille and Slam Panel

Slam Panel - panel beating

In order to have a solid mount for making the bonnet, I started the slam panel. It needs to be strong, so a simple piece of tin would not be enough. This panel needed to be part of something bigger, how big I didn’t know, so I started by cutting the outline shape and rolling in a simple pattern.

Even without a clear vision of what I was making, this grille shell was going to be a massive challenge. – my biggest yet

As it stood, it would not be anywhere near strong enough. I did not want something that weighed a couple tons, so I was going to make the whole grille surround and slam panel into one combined panel. I used 18awg steel and to stop everything from ‘oil canning’, I used the bead roller. The under-side of this panel will need a lot of support.

The internal framework has a secondary function. I want all the air passing through the grille to either go through the radiator or into the twin air filters. There will be an under-tray that will continue to guide the air through the oil cooler and over the engine.

I’d previously done some measurements and sums that said cooling on this car was marginal. I therefore needed to ensure all the incoming air could not simply pass around the radiator. Whilst stationary, I want air to get sucked through the twin fans, then over the engine and not just straight back out the front. I want air to exit either through the louvres by the exhaust or out the vents in the side of the bonnet.

Slam Panel - panel beating

The slightly rusty ‘U’ section the slam panel sits on is just for mocking-up purposes. This shape will eventually be formed by the bonnet sides and the grille shell.

The bonnet edge will not be straight. It will come down similar to a 1937 Chevy.

1937 Chevy Coupe Grill

Currently I have a P38 serpentine Rover V8, with a single air filter. I’m swapping this for a Thor V8 with cross over plenum and twin MGF throttle bodies. With this set-up, I’ll have two cone shaped 70mm air filters. This is not a performance upgrade, this is purely down to having a symmetrical looking engine bay.

Rover V8 Throttle Bodies

With these pointing forward behind the grill, at speed, air will be force fed into the induction system.

Slam Panel - panel beating

As always I’m just making this up as I go, so I started by cutting out the hole for the radiator fan and mocking up the air filters. I wanted the filters to provide a solid mount for the slam panel. So I started with some cylinders to direct air into the filters.

Slam Panel - panel beating

Making Templates

There were quite a few pieces of steel going into this panel. I had an approximate idea of what I wanted but in reality this was a fluid design that evolved with every piece. I’ll work out one side, then mirror it when I’m happy.

I’ve developed a technique, that I call ‘Gaffa tape modelling’. I’ll cut a hole; like around the fan; then bridge said gap with hundreds of strips of tap. I then take a knife and cut a piece out I can use as a template.  As you’d expect, they don’t quite lay flat but often it’s surprising how little shrinking and stretching a distinctly contoured panel needs to become 3D.

Slam Panel - panel beating

This tape is one side of the fan surround. I simply flipped it to make it’s mirror. With it’s steel counterpart, just 6 pulls of the stretcher and a bend around a fence post gave me the shape I wanted. Maybe for my next fabrication challenge I’ll go for a bigger jigsaw with fewer pieces.

Slam Panel - panel beating

Around the hole for the radiator fan, I’ll put some rubber edging. Hopefully that should stop any annoying squeaks and help prevent any wear. When I tested the air-flow through a radiator, I was gob smacked by the improvement an air-tight fan shroud made. Ensuring all air passed through the radiator dropped the cooling time from 121 to 38seconds. If the incoming air could simply pass around the fan, that effort gone into the shroud is wasted.

Plus, it gives the nose that Thrust 2 rocket car look.

I had to drop the air filters by nearly 2″, which puts them pretty close to the radiator. The gap between the air filters is where the expansion tank will sit, so I’ll need to cut another cut-out to clear that.

When I want to recess an odd shape into another shape, the hole I need to cut isn’t obvious. I therefore shine a laser pointer through one object to see what outline it leaves on the other.

Slam Panel - panel beating

Slam Panel - panel beating

Another Weekend – The bonnet latch takes shape

Recently, the Doc’s have told me I’m ‘not going to have much energy for hobbies‘ and maybe I should consider ‘part-time work‘,
but what do they know?
I must admit the climb upstairs to bed, was ridiculously tough and didn’t have the energy for my lunchtime walks.

I’ve recessed an MG TF bonnet catch into the Grille about 1cm. They’re a neat little height adjustable catch.

  • Catch – FPB100110
  • Latch – FPS10007
  • Plate – FPT10005

MG TF bonnet catch

Bespoke Bonnet

I also started to recess the air filters into the grille. Unfortunately, I discovered they are highly flammable.
boy that thing went up quick!

Slam Panel - panel beating

With the passenger side done, I could take some templates to make the other side.

Slam Panel - panel beating

The Challenge of Panel Beating

What I’m starting to learn, is that some ripples in bodywork can be a fraction of a millimetre deep yet show up instantly in photos. The LED lighting in my workshop is hopeless and spotting distortion isn’t too easy, however a camera tells no lies. 

Looking at the photo below, it looks like my bulkhead has been given a good kicking; then left to rust. There is no way this would look good painted. Yet when I place a straight edge over a dent it can be hard to spot or even feel. Part of me wants to get it perfect, the other half just says skim some mud over it and block it out. 

I’m sure I could seam weld it, run a body file over it and my concerns would disappear – for a while.

Bulkhead - Panel Beating

To shrink or stretch away that distortion can take either lots or minimal effort (no middle ground).

What often surprises me is, the effort required to correct a huge dent is tiny – When I get it right!

I’m a complete novice and Panel Beating doesn’t come naturally.

I spent 7 years at University and cycled 1,500 miles across 11 counties in 10 days, yet Panel Beating is by far my biggest challenge yet.

I’ll see simple panel beating tools at car shows and think…..

  • What does that do?
  • Why not just use a regular hammer?
  • Does that tool work or is it just a gimmick?
  • Surely, I don’t need that, can’t I just take a magic shortcut?

What can be frustrating, is spending endless hours making a panel only to realise it is either a buckled patchwork or so thin it’s simply fit for the bin. All those hours of work have produced another prototype or template for the 2nd, 3rd or even 4th version.

Also, if a dent a fraction of a millimetre deep is obvious, wouldn’t the eye pick up a profile difference of 2mm from one side to another. How accurate do a pair of wing have to be? I thought Hobbies were supposed to be relaxing?

Slam Panel - panel beating Slam Panel - panel beating

Another Week – More work on Grille

I’ve not done too much recently, due to time and health, but a little ‘visual’ progress has been made on the grille framework.

Slam Panel - panel beating

In the side shot above, you can see I’ve bent a few bits of 5mm round steel bar to represent the bonnet lines. Currently the bonnet top slopes down 1.5°, but I think I’ll increase that to closer to 3° as I want the bonnet shallower at the front. The central grille support bar has a slight curve to it, but again that may increase.

The grille profile will be a cross between a ’37 Chevy and a ’37 Ford. The bonnet sides will sweep down to meet the curve of the grille.

The central bar with the dimple die’d holes, will have numerous cut-outs to support the horizontal grille bars. It will also have some more lightweight bracing panels to stop the whole assembly distorting when I slam the bonnet.

Slam Panel - panel beating

The look I’m going for is a more retro version of the 1937 Ford look-alike below. Mine will be a little more 1940’s Aero / Steam punk look.

Hot Rod 1937 Slantback

Note how shallow the bonnet is at the front and the way it’s lines flows into the curved grille. I like the shallow look, but on my car, some of that effect will be taken away by the Chevy style, swept down bonnet side edges. 

I’ve never drive my car, but as I’m building, BIVA radii specs are always in my mind. Therefore, a couple of the grille edges will need to be ‘blunted’, but if I’m mindful of the spec, nothing will present a real problem. 

BIVA External Radius Spec

DVSA uses a 100 mm sphere to assess the exterior. A tip from Kev at RodsNSods, means I have a 100mm cake decorating ball at the ready.

Anything that is contactable is checked with a radius gauge. Any hard part that the sphere touches must be ‘radiused’ to at least 2.5 mm or any items that project:

  • more then 5mm needs to ‘radiused’ to 2.5mm
  • less than 5mm needs to be blunted

A sharp edge may cause an injury, whereas a ‘radiused’ or a blunt edge/corner may cause less of an injury.

Check the exterior of the vehicle by look and touch to see what you think may cause injury. This is what DVSA will look for.

See section 16 (exterior projections) of the IVA inspection manual for the full inspection standard. Also see:

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